Solar trough mirror frame, rolling rib, roller, cleaning apparatus and method

ABSTRACT

A support system for holding solar mirrors of a solar trough system includes a frame for supporting the mirrors. The system includes a rib attached to the frame. The system includes at least a first roller engaged with the rib along which the rib moves as the frame moves. A method for moving a frame supporting solar mirrors of a solar trough system includes the steps of moving the frame on a roller guided by a rib engaged with the roller and attached to the frame bottom to a first position. There is the step of moving the frame on the roller guided by the rib engaged with the roller and attached to the frame bottom to a second position. A roller for engaging with a rib attached to a frame that holds mirrors of a solar trough system. A rib for a frame that holds solar mirrors of a solar trough system which engages with a roller. A support system for mirrors of a solar trough system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. provisional application Ser. No.61/195,087 filed Oct. 3, 2008. This application is acontinuation-in-part of U.S. patent application Ser. No. 12/583,787filed Aug. 26, 2009, which is related to U.S. provisional applicationSer. No. 61/190,573 filed Aug. 29, 2008, all of which are incorporatedby reference herein.

FIELD OF THE INVENTION

The present invention is related to a support system for holding solarmirrors of a solar trough system. (As used herein, references to the“present invention” or “invention” relate to exemplary embodiments andnot necessarily to every embodiment encompassed by the appended claims.)More specifically, the present invention is related to a support systemfor holding solar mirrors of a solar trough system using a rib attachedto a frame of the support system that moves along rollers, and a systemfor cleaning the mirrors which can be used with this or other CSP(concentrated solar power) frame systems.

BACKGROUND OF THE INVENTION

This section is intended to introduce the reader to various aspects ofthe art that may be related to various aspects of the present invention.The following discussion is intended to provide information tofacilitate a better understanding of the present invention. Accordingly,it should be understood that statements in the following discussion areto be read in this light, and not as admissions of prior art.

The parabolic trough design of concentrated thermal solar frames usesparabolic mirrors to focus and concentrate the sun's energy on aninsulated tube filled with heat transfer fluid; this fluid is heated togenerally well above 700 d.F. and circulated to a steam turbine powergeneration plant (See FIGS. 1 and 2).

FIG. 1 is a schematic of concentrated solar parabolic trough system.Parabolic mirrors rotate to track the sun as it traverses the sky. FIG.2 is a schematic that shows the concept of the parabolic mirrorsconcentrating the sun's rays onto a small diameter collector tube at theparabola's focal point.

The frames supporting these structures are large, stiff truss-likestructures designed to support the weight of the mirrors and the windloads (which can be substantial) in a manner which both keeps the unitsstructurally sound and minimizes deflections to achieve high conversionefficiencies of the sunlight into energy; any deflections reduce thisefficiency.

The frames pivot about a line which is generally the center of mass ofthe minors, tubes and frames combined; this pivoting enables the mirrorsto “track” the sun as it traverses across the sky. The current designsuse elevated pivot points at each end of the frame with bearings, anddrive arms which transfer the rotational forces from one frame toanother (a single drive unit turns several frames in the row);generally, these end supports require large footings.

A simple, practical design to dramatically reduce the loads on the pivotpoints 34 and upon the frame members, resulting in less deflection andimproved optical alignment has been developed. This is called the“Rolling Rib” design (and derivations of it, including the incorporationof minor washing and water reclamation integrated into any solar framedesign).

BRIEF SUMMARY OF THE INVENTION

The present invention is related to a support system for holding solarminors of a solar trough system. The system comprises a frame forsupporting the minors. The system comprises a rib attached to the frame.The system comprises at least a first roller engaged with the rib alongwhich the rib moves as the frame moves. The ends of the rib may haveslight bevels to engage more easily when first in contact with thecurvature of the roller(s).

The present invention pertains to a method for moving a frame supportingsolar mirrors of a solar trough system. The method comprises the stepsof moving the frame on a roller guided by a rib engaged with the rollerand attached to the frame bottom to a first position. There is the stepof moving the frame on the roller guided by the rib engaged with theroller and attached to the frame bottom to a second position.

The present invention pertains to a roller for engaging with a ribattached to a frame that holds mirrors of a solar trough system. Theroller comprises a housing which receives the rib. The roller assemblycomprises a roller or rollers disposed in the housing on which the ribmoves when the frame moves.

The present invention pertains to an apparatus for cleaning solarmirrors on a frame of a solar trough system. The apparatus comprises aspray assembly for spraying fluid on the mirrors. The apparatuscomprises a gutter mounted to the framework which collects the fluidsprayed on the minors.

The present invention pertains to a method for cleaning minors on aframework of a solar trough system. The method comprises the steps ofspraying fluid on the minors with a spray assembly. There is the step ofcollecting the fluid sprayed on the minors with a gutter mounted to theframework. There is the step of directing the fluid in the gutter to adesired location.

The present invention pertains to a rib for a frame that holds solarmirrors of a solar trough system which engages with a roller. The ribcomprises a profile having a top portion that attaches to the frame, acentral portion extending from the top portion and a bottom portion thatengages with the roller. The rib moving along the roller as the framemoves.

The present invention pertains to a support system for mirrors of asolar trough system. The system comprises means for supporting themirrors. The system comprises a rib attached to the frame. The systemcomprises roller means engaged with the rib along which the rib moves asthe supporting means moves.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawings, the preferred embodiment of the inventionand preferred methods of practicing the invention are illustrated inwhich:

FIG. 1 is a schematic of concentrated solar parabolic trough system.

FIG. 2 is a schematic which shows the concept of parabolic mirrorconcentrating the sun's rays onto a small diameter collector tube at theparabola's focal point.

FIG. 3 shows an end view of a “Series 5” (5 triangles as viewed from theend) Parabolic Frame with “Rolling Rib” system and with a mirrorcleaning system.

FIG. 4 shows the “Series 5” design with 5 triangles as viewed from theend, depicting the radius of “Rolling Rib” required.

FIG. 5 is a top view of two frames side by side, each with four rows (A,B, C & D) of seven (7) mirrors.

FIG. 6 is a cross section of a “Series 5” solar frame with central pivotpoint and four (4) rollers on the arc of the bottom of the “RollingRib”.

FIG. 7 is the “Rolling Rib” frame with four (4) roller assemblies with acurved rib and with a mirror cleaning “gutter” collector depicted.

FIG. 8 shows the cross sectional profile of an extruded rib to bestretch-formed into a circular curve to become the “Rolling Rib”.

FIG. 9 shows the cross sectional profile of the extruded roller housingswith holes for inserting shafts on which the rollers will turn.

FIG. 10 shows the cross sectional profile of the extruded roller housingwith the cross sectional profile of the “Rolling Rib” shown inserted andsupported by one large roller underneath and two smaller rollers above.

FIGS. 11 a and 11 b show a representation of a “Rolling Rib” showing theRib bending upwards emerging from the housing with rollers.

FIG. 12 shows a short section of a “Rolling Rib” system with rollers.

FIG. 13 a shows a curved rib.

FIG. 13 b shows the rib supported by one roller assembly.

FIG. 14 is a representation of three (3) of the four (4) rollerassemblies on a support structure with the bottom two “constraining” thecurved “Rolling Rib” I-beam.

FIG. 15 is a representation of a “Rolling Rib” device shown at a greaterrotated angle with the bottom two of four roller assemblies shown“constraining” the curved I-beam.

FIGS. 16 a-16 c show side views of a design of a Parabolic Frame in 12meter and 16 m configurations. FIG. 16 a shows the normal existingconfiguration with a 12 m frame supported from each end. FIG. 16 b showsa configuration with a single rolling rib supporting the center of a 12m frame in addition to the support from each end. FIG. 16 c shows tworolling ribs supporting a longer (16 m) frame in the mid section inaddition to the support from each end.

FIG. 17 a is a “Rolling Rib” design with four rollers & frame. Note thatthe roller assemblies are depicted as a single bottom roller only forclarity—top rollers would likely be included as well to counteract windforces acting on the back of the parabolic mirrors.

FIG. 17 b is a “Series 5” geometry of frame design with curved extrusion“Rolling Rib” attached underneath via truss-like structure and foursimple circles depicting roller assemblies supporting it.

FIG. 18 a shows the orientation of the “Rolling Rib” (95 degrees of thecircumscribing circle) with four (4) rollers depicted placed to supportthe frame upon rotation.

FIG. 18 b shows the “roller” engagement when the frame is rotated 18degrees (2 roller assemblies supporting the frame).

FIG. 19 a shows at 23 degrees of rotation, three (3) roller assembliesare “engaged” supporting the frame.

FIG. 19 b shows at 47 degrees of rotation, two (2) roller assemblies are“engaged” supporting the frame.

FIG. 20 a shows at 70 degrees of rotation, two (2) roller assemblies are“engaged” supporting the frame.

FIG. 20 b shows after 70, and certainly at 90 degrees of rotation, onlyone (1) roller assembly is “engaged” and supporting the frame.

FIG. 21 shows an alternative “Rolling Rib” design, where rollerassemblie(s) are attached to the bottom of the solar frame (byadditional trusses or directly to the solar frame if geometry permits),and the “rib” is attached to the footings framework.

FIG. 22 shows a rack/pinion drive design for a “Rolling Rib”.

FIG. 23 shows a mirror cleaning and solution reclamation system. Whilethis is depicted on a “Rolling Rib” system, it is equally applicable toother frame systems.

FIG. 24 shows a gutter with a closed cap.

FIG. 25 shows a gutter with the cap open, with cleaning solutiondepicted dripping from the mirror edge into the gutter.

FIG. 26 is an end view of “Series 5” geometry solar frame, “Rolling Rib”including roller assemblies and water spray system/reclamation gutter.

FIG. 27 is a side view of solar frame, “Rolling Rib” and water supply,gutter and drain lines.

FIG. 28 is an overview of water supply, “Y” splitting the water betweenthe spray nozzles and the gutter and other features.

FIG. 29 is a close-up of roller assemblies guiding curved rib and guttersystem including water supply to pressure tube which fills to rotate thedevice, thin drain line into gutter, main drain and simple snap fitgutter mounting upright.

FIG. 30 is a close-up of a gutter showing how it snapfits into themounting bracket.

FIG. 31 shows a “360 degree rib” design showing the solar frame in asideways position.

FIG. 32 shows a “360 degree rib” shown with parabolic mirror pointingstraight down, with the 360 degree “Rolling Rib” continuing to providesupport through all four (4) roller assemblies.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals refer tosimilar or identical parts throughout the several views, and morespecifically to FIGS. 3 and 4 thereof, there is shown a support system10 for holding solar mirrors 12 of a solar trough system 8. The system10 comprises a frame 14 for supporting the mirrors 12. The system 10comprises a rib 16 attached to the frame 14. The system 10 comprises atleast a first roller assembly (note: the term roller assembly is used asit suggests a system supporting the “Rolling Rib” both from above andbelow, but it can also refer to designs with a single roller) 18 engagedwith the rib 16 along which the rib 16 moves as the frame 14 moves.

The present invention pertains to a method for moving a frame 14supporting solar mirrors 12 of a solar trough system 8. The methodcomprises the steps of moving the frame 14 on a roller assembly 18guided by a rib 16 engaged with the roller assembly 18 and attached tothe frame 14 bottom to a first position. There is the step of moving theframe 14 on the roller assembly 18 guided by the rib 16 engaged with theroller assembly 18 and attached to the frame 14 bottom to a secondposition.

The present invention pertains to a roller assembly 18 for engaging witha rib 16 attached to a frame 14 that holds mirrors 12 of a solar troughsystem 8. The roller assembly 18 comprises a housing 20 which receivesthe rib 16 and supports the rollers. The roller assembly 18 is comprisedof rollers 18 a, 18 b & 18 c disposed in the housing 20 on which the rib16 moves when the frame 14 moves.

The present invention pertains to an apparatus 24 for cleaning solarmirrors 12 on a frame 14 of a solar trough system 8. The apparatus 24comprises a spray assembly 26 for spraying fluid on the mirrors 12. Theapparatus 24 comprises a gutter 28 mounted to the framework whichcollects the fluid sprayed on the mirrors 12.

The present invention pertains to a method for cleaning mirrors 12 on aframework of a solar trough system 8. The method comprises the steps ofspraying fluid on the mirrors 12 with a spray assembly 26. There is thestep of collecting the fluid sprayed on the mirrors 12 with a gutter 28mounted to the framework. There is the step of directing the fluid inthe gutter 28 to a desired location.

The method preferably includes the step of moving the mirrors 12 intoposition for spraying.

The present invention pertains to a rib 16 for a frame 14 that holdssolar mirrors 12 of a solar trough system 8 which engages with a rollerassemblie(s) 18. The rib 16 comprises a profile 40 having a top portion42 that attaches to the frame 14, a central portion 44 extending fromthe top portion 42 and a bottom portion 46 that engages with the roller18 (the bottom portion 46 is shown slightly slanted such that it is morelikely that dirt and debris do not collect). The rib 16 moves along theroller assembly 18 as the frame 14 moves. Also note that the ends of the“Rolling Rib” may be beveled to ease initial contact with the curvedrollers.

The present invention pertains to a support system 10 for mirrors 12 ofa solar trough system 8. The system 10 comprises means for supportingthe mirrors 12. The system 10 comprises a rib 16 attached to the frame14. The system 10 comprises roller means engaged with the rib 16 alongwhich the rib 16 moves as the supporting means moves.

The supporting means can be the frame 14. The roller means can be theroller assemblie(s) 18.

In FIG. 3, there is shown an end view of “Series 5” geometry design (5triangles viewed from the end) of a Parabolic Frame showing the pivotpoint 34, the Extra center support 38, the additional “Rib” 16supporting the underside of the frame and a “Rolling Rib” framestructure to support the rotating Solar Frame with four (4) rollersdepicted (as few as one or as many as desired roller assemblies can beutilized). Also shown are mirror washing and water collection devices. Agutter system for mirror cleaning and water reclaim may be used. Thegutter cap can be fixed or have the ability to rotate by water pressureactuators or by lever action to keep dirt, debris, sand, etc. fromaccumulating.

In the operation of the invention and referring to FIG. 4, there isshown an end view of a “Series 5” geometry design (5 triangles viewedfrom the end) of Parabolic Frame 14 showing the pivot point 34, theextra center support 38, the additional “Rib” 16 supporting theunderside of the frame 14 and a “Rolling Rib” frame 14 structure tosupport the rotating solar frame 14 with four (4) rollers. Also shownare mirror washing and water collection devices. Looking at a crosssection of a frame 14 (in FIG. 4 for the “Series 5” design), such thatone can see the parabolic shape of the mirror 12: by drawing a line fromthe pivot point 34 (small circle at the “start” end of the arrow) to thefarthest tip of the mirror 12 (point end of the arrow) the minimumradius of a circumscribing circle can be defined that defines thetraverse of the outermost parts of the mirror 12. This large circle waschosen to enable the frame 14 to pivot 360 degrees without worryingabout interference between with the mirrors 12 and the roller assemblies18; smaller diameters are certainly possible, if the supports and roller18 assemblies (described below) fall between the mirror sections whichare separated sufficiently along the length of the frames 14 (forexample, between mirrors 3 and 4 and 4 and 5 for a 12 meter frame 14with 7 mirrors along its length (numbering depicted in FIG. 5)). 35 isthe minimum “rib” diameter so that mirrors clear it during rotation.

FIG. 4 shows the “Series 5” geometry design with 5 triangles as viewedfrom the end. (Pivot point 34 as small circle above parabolic mirrors 12with the arrow drawn from the circle representing the minimum radius ofthe circumscribing circle).

FIG. 5 is a top view of two frames side by side, each with four rows (A,B, C & D) of seven (7) mirrors. Arrows point to most likely a highdeflection/force area.

Looking at the cross section of the frame 14 (FIG. 6) and the mirrors12, the maximum loading of the system 10 occurs due to a combination ofwind load, weight and the torque of a line of these mirror/frameassemblies driven from a central rotational drive. For discussionpurposes, the maximum loads and deflections will occur at the center ofthe parabolic span, at the intersection of mirrors B4 and C4 (FIG. 5)(depending on wind loading and the “flow” of air over the mirror indifferent orientations, the wind loading is not likely exactly equal toan evenly loaded lbs/sq. ft. calculation). The trusses of the frame 14(FIG. 4) are designed as larger members at this point to deal with thelarger resulting tensile and compressive forces (in FIG. 4, note the twolargest/thickest struts 30 forming the inside “V” at the very bottom ofthe frame 14.

The frame 14 designs should take into account wind load conditions inall different possible orientations of the mirror direction. Undercertain wind conditions, the frame 14 may rotate to take it out ofservice to protect it, but in many instances, the high wind loads occurduring normal operational periods. The focal length of the parabolicmirror shape is critical to focus the maximum energy on the solarcollector tube—any frame 14 deflections reduce this intense focus (seeFIG. 2). Depending on what direction the mirrors 12 are pointed, and thedirection/intensity of the wind load, the system 10 can be subject toloads from the weight of the frame 14, the pressure (or lift) of thewind and any torque induced into the structure by the rotationalmechanism trying to rotate the mirrors 12 into some position resisted bythe long line of mirrors 12 being “torqued” in an opposing direction bywind forces, driven by a drive mechanism immediately next to someframes, but often transferred from this drive frame to the next, andfrom the next to the next following, etc.

Generally, the wind loads will act upon the mirrors 12 either “pushing”them into the frame 14 structure or attempting to lift them off of theframe 14 structure. The mirrors 12 are attached to mirror supports,which in the “Series 5” frame 14 and shown throughout this document arethemselves attached to three I-beams 32 approximating the parabolicshape of the mirrors 12. Please note that the “Rolling Rib” design canbe adapted to alternative frame geometries or designs; the “Series 5”was chosen as a single design upon which to depict the “Rolling Rib” tosimplify the explanation; for example, frame designs using other mirrorsupport means, no I-beams, etc. . . . can still use the “Rolling Rib”concept. These I-beams 32 are equipped with four (4) “sleeves” fastenedunder them, through which main support members extend and are fastened;this system 10 holds the seven (7) I-beams 32 under the frame 14 at thepreset intervals. The bottom of the frame 14 truss-structure uses three(3) additional sleeve/main support connection lines. The seven (7)sleeves are connected by a series of specially designed struts 30 (withspecifically designed strut 30 end pieces incorporated). All of theelements discussed in this paragraph combine to create the space frame14 which is the WES “Series 5” design solar frame 14. The entire frame14 is hung from two rotational positions at either end of the 12 meterlength. For explanatory purposes, a 12 meter frame is discussed, but theconcepts apply equally well to 8 m, 16 m or other lengths of framesystems.

The wind and weight loads either “pushing” into the I-beams 32 orlifting off of them are thus transferred through these pinned strut 30connections through the truss structure. The entire frame 14 is thussubject to large, complex loading conditions, with the most deflectionlikely occurring near the center of the 12 meter length, although withrotational torques, the loading is too complex for this assumption to bestrictly accurate (structural analysis software modeling all load casesreveals the precise results for each frame design). The “Rolling Rib”design discussed below provides excellent support at this criticalcentral location to minimize loads and deflections on the solar frame 14system 10, resulting in lower deflection and better solar conversionperformance.

Without the “Rolling Rib” system 10, to overcome these forces and theassociated deflections, as currently designed the truss members (FIG. 4)must be made stronger and the overall truss “deeper”. This causes twoproblems: First, the weight (cost) of the structure increases withincreasing material content (diameter, wall thickness and strut 30length). Second, compounding the first issue is that as the truss ismade “deeper”, the strut 30 lengths increase; calculations have shownthat the failure mode on these structures can be due to compressivebuckling of the long strut 30 members. To avoid this, diameters/or wallthicknesses must be increased even further than deflection calculationsalone would suggest.

The “Rolling Rib” design introduces an additional structural member (oneis likely for a 12 meter long frame 14, perhaps more for longer frames).This “rib” 16 is attached to the bottom of the solar frame 14 (FIG. 4)either directly if the geometry allows or by truss-like members as shownin the figures. Due to the pivot points 34 of the frame 14 and thestructure, the “rib” 16 will be subject to either compressive or tensileforces through the struts 30 connecting it at the cross sectionalconnection point of the solar frame 14 these forces transfer through theroller assemblies 18.

For drawing simplicity/explanation, these roller assemblies 18 are oftenshown in many of the overall figures as single rollers 18, which wouldinfer that they only support the solar frame 14 from loads “pushing”into the frame 14; the roller 18 assemblies actually are designed totake both the “pushing” loads into the frame 14 and the “lifting” loadsthat would occur if the wind, for example, were to be pushing on theunderneath portion of the parabolic mirrors 12 (see FIGS. 7, 10, 11 b,12 and 13 b).

The purpose of this “rib” 16 is to allow wind/weight/torque forces fromthe solar frame 14 to be transmitted in a more direct fashion to theground/foundations vs. trying to do so at only two points at either endof a 12 meter (or other length) span, as is currently the design. Bybreaking the spans into two or more smaller “spans”, and providing theability to support the structure mid-span, forces and deflection in thisregion will be much lower and mechanical and optical performanceenhanced.

FIG. 6 is a cross section of “Series 5” solar frame 14 with centralpivot point 34 and four (4) roller assemblies 18 on the arc of thebottom “rib” 16. The roller assemblies 18 constrain the “rib” 16 toprovide support no matter what the wind/weight/torque load (“pushing” or“lift” as well as sideways). As shown in this tilt configuration, three(3) roller assemblies 18 support the frame 14 in addition to the centralpivot points 34 at either end of the 12 meter frame 14.

FIG. 7 is a cross section of the four (4) roller assemblies 18 withcurved “rib” 16.

Stretch-forming aluminum extrusions enable very accurate curvatures tobe achieved. In this existing industrial process, aluminum extrusions orother lineals are gripped and put under tension as they arepulled/bent/formed around the shape creating the ID of the curve. Thedesign here is to stretch-form part of a “perfect” circle. This iscurrently designed with an arc length of approximately 97 degrees, witha length of approximately 16 ft. 9 inches, to exceed the pivot point 34to mirror tip (shown as an arrow in FIG. 4) radius of 118″ (currently,the pivot point 34-to-“rib” 16 radius is drawn at 118.6″). This “rib” 16is extruded from a 6000 series aluminum alloy (like 6005A or 6105) andeither aged then stretch-formed or stretch-formed and then aged. It isthen attached to the bottom of a solar frame 14 with appropriate struts30 such that the center of the arc/circle perfectly coincides with thecenter of rotation of the solar frame 14; this extrusion would be like a“rib” 16 under the frame 14, at desired points/intervals along thelength of the frame 14 breaking the span into two, three or moresections (See the truss-like cross section at the bottom of theparabolic frame 14 in FIG. 6). Other materials than aluminum, otheralloys/tempers of aluminum extrusions and other means thanstretch-forming are possible to create the curving/bending/shape.

Mounted to the ground would be roller assemblies 18 supported by asimple framework (See FIGS. 3 and 7) which would guide the circular arcstretch-formed extrusion, helping to support the weight/wind load inwhatever direction it bears (there would be rollers under the circulararc extrusion and over it as well). Multiple easilyextrudable/assemble-able designs have been developed by WES for thispurpose (see FIGS. 8-13 b). The “ribs 16” could have bearing/wearsurfaces (like high density polyethylene or other polymer) inserted intothe extrusion as spacers and stretch-formed with the extrusion but asimpler design, with easily replaceable high density (high densitypolyethylene for example) polymer rollers 18 or wheels 22 bearing on thecurved, stretch-formed aluminum extruded “modified” I-beam 32 is shown.The surfaces pointing upwards would be angled to allow dirt/debris toslide off.

FIG. 8 shows an extruded rib 16 to be stretch-formed (or otherwiseformed) into a circular curve. The top surfaces of the bottom flange areangled to help allow dust and debris to slide off. FIG. 9 shows extrudedroller assembly 18 housings 20—cross sectional profile which would becut to length—to support one bottom roller 18 a and two top rollers 18 band 18 c to guide curved “rib” 16. In the design discussed, there willbe four of these roller housings 18 for each “rib” 16. The housing 20has a first segment 48 in which the first roller 18 a is disposed, asecond segment 50 in which a second roller 18 b is disposed, and a thirdsegment 52 in which a third roller 18 c is disposed. FIG. 10 is a crosssection of curved “rib” 16 inserted into one roller assembly 18 withhousing 20 with rollers 18 a, b and c shown constraining it.

FIGS. 11 a and 11 b show a representation of a “Rolling Rib” showing rib16 bending upwards. Note that the two ends of the rib 16 will be beveled(not just cut straight across as shown in the figure) so that thesurface of the rib 16 approaching the roller 18 is guided into positionby the combination of the curvature of the roller 18 and the beveled rib16 end. FIG. 12 shows a “Rolling Rib” system with wheels 22 or rollers18. FIG. 13 a shows a curved “rib” 16. FIG. 13 b shows the “rib” 16supported by one roller assembly 18.

FIG. 14 is a representation of three (3) of the four (4) rollerassemblies 18 on a support structure with the bottom two “constraining”the curved I-beam 16. It should be noted that the actual support frame14 will not be made up of square members as depicted, but will likelyutilize structural aluminum extrusions or other materials. Also note thewater collection “gutter” next to the left most roller assembly 18(discussed below); this gutter 28 will of course not just be a shortcross section but will extend the full length (12 meters in this case)of the mirror 12. FIG. 15 is a representation of a “Rolling Rib” deviceshown at a greater rotated angle.

The design divides up the long spans (8, 12, 16, . . . meters) by usingone or more of these circular “ribs” 16 under the solar frame 14(alternatively, the rollers could be mounted to the solar frame 14 andthe ribs 16 could be mounted to the ground through a structure, althoughthis might lead to more dust/dirt collection in the ribs 16) (see FIG.21). For example, a 12 meter long frame 14 might have one “rib” 16 inthe center, essentially partially breaking the span into two 6 meterspans (the end supports would be at 12 meters but the center “rib” 16would support much of the weight and wind load). A 12 meter frame 14could of course also have 2 or more ribs 16, although as currentlydesigned, each rib 16 requires between two and four extra footings inthe ground (two could be used with an I-beam 32 spanning them to providethe attachment surface for the roller assemblies 18 (currently shown asfour roller assemblies 18 per solar frame 14 “rib” 16, but could be asfew as one or as many as desired). See FIGS. 16 a, 16 b and 16 c.

The ultimate goal is to allow the “rib” 16 base of the solar frame 14 totransmit some of the load through the roller 18 assemblies to thefoundations in the ground, reducing the forces and deflection on theframe 14, and thus improving the optical alignment, performance andresistance to damage due to high wind loads. For example, for a 16 meterframe 14, there might be two “ribs” 16 breaking the spans into thirds.For a 12 meter frame 14, if there were only 1 “rib” 16 centered, if itwere to be positioned such that there weren't struts 30 directly aboveit for the specific current “Series 5” design, there might be anadditional vertical strut 30 dumping the load from the mirror 12 throughthe mirror 12 supports more directly into the “rib” 16 and rollerassemblies 18 into the footings (see strut 30 shown as 38 in FIG. 17 a),which is why the extra center vertical strut 38 is shown for the 12meter design (see the top of FIGS. 16 a and 16 b).

FIGS. 16 a-c shows a Side View of design of Parabolic Frame 14 in 12meter and 16 meter configurations. FIG. 16 a shows that if the “RollingRib” design is to be used in the center of the span for a 12 m frame, anextra center support 38 should be added. (In FIG. 16 b, the “Rib” 16 isshown, but it partially obstructs the view of the extra support rib 16).FIG. 16 c illustrates how multiple “Rolling Ribs” may be used to furtherbreak longer spans into shorter sections, each of which will have lessdeflection under load (weight & wind, for example).

FIG. 17 a is a “Rolling Rib” design with four roller assemblies 18 andan extra vertical strut 38. FIG. 17 b is a frame 14 design with curvedextrusion “rib” 16 attached underneath via a truss-like structure; thebottom is shown in black with drive wheels of a gear driven mechanism(discussed below).

FIG. 18 a shows the orientation of the “Rib” 16 (95 degrees of thecircumscribing circle) with four (4) roller assemblies 18 placed tosupport the frame 14 upon rotation; FIG. 18 b shows the “roller”engagement when the frame 14 is rotated 18 degrees (2 roller assemblies18 supporting the frame 14). FIG. 19 a shows the same at 23 degrees ofrotation, with three (3) roller assemblies 18 “engaged” to support theframe. FIG. 19 b shows the same at 47 degrees of rotation, with two (2)roller assemblies 18 engaged to support the frame 14. FIG. 20 a showsthe same at 70 degrees of rotation, two (2) roller assemblies 18 engagedto support the frame 14. FIG. 20 b shows the same after 70, andcertainly at 90 degrees of rotation, with only one (1) roller assembly18 engaged to support the frame 14.

FIG. 21 shows an alternative “Rolling Rib” design, where rollerassemblie(s) 18 are attached to the bottom of the solar frame 14directly or through intermediate structural pieces and the “rib” 16 isattached to the footings framework. This simplifies the design but mayhave issues with dust/debris on the “rib” 16 track. A similar “rollerassembly” can be used to that described elsewhere. There is a guttersystem shown for mirror cleaning water reclaim. The gutter 28 cap 58 canbe fixed or have the ability to rotate by water pressure actuators or bylever action to cover the gutter and keep sand, dirt or debris fromaccumulating.

A drive design (may be additive to or instead of the above advantages)is shown in FIG. 22. The bottom surface of the “rib” 16 could beequipped with a “rack” 56 attached to the rib 16 such that a “pinion”gear could drive the rotation of the unit from a hydraulic motor or anyother device providing rotational forces. FIG. 22 shows a rack 56/piniondrive 54 design for a “Rolling Rib” 16 design. Currently, the CSP frames14 are often driven from a single drive mechanism operating two, three,four or more frames 14 on either side of the drive unit. The frame 14furthest from the drive unit is free to rotate on one end and rotatedinto the correct position to face the sun by a connection to the nextframe 14 closest to the drive mechanism. This frame 14 thus sees torqueon one end, as in turn rotated by the NEXT frame 14 closest to the drivemechanism. The final frame 14 directly attached to the drive mechanismis thus subject to not only any torques induced by wind loads on itself,attempting to turn it from perfect focus on the sun, but also to thetorques from ALL of the other frames 14 driven by it (n−1 frames 14worth of torque is applied to one end of it, and the other end isattached to the drive motor). The concept of using a shaft drive orother means rotating the pinion gear 54 under each curved gear rack 56attached to/part of some or all of the curved ribs 16, totallyeliminates the torque applied to all frames 14 from other frames 14,allowing for lighter, more efficient structural designs of frames 14;the “drive torque” is separated from the wind torque of each individualframe 14.

Use of the “Rolling Rib” to enhance security of solar frames during highwind conditions:

Concentrated Solar Power frames can be used in areas with high windloads (hurricanes in Florida, dust storms in the plains, etc.). Theincorporation of a modified “Rolling Rib” provides additional protectionfrom damage in these installations. The concept is to extend the“Rolling Rib” to part or all of a full 360 degree circle (currentlyshown as approximately 97 degrees in the prior pages). To accomplishthis, it is likely that the “360 degree circle” could be made up of twoor more partial segments, connected together (this is a simpler way tostretch-form these large structures, although similar aluminum extrudedbicycle wheels have been fabricated for decades). It is also likely thatthe “rib” 16 would need additional support for stabilization (structuralpiece 38 shown in FIGS. 31 and 32).

The “360 degree rib” (named to indicate that the rib can extend toencompass up to the full circumference of the rotational path) enablesthe solar frame 14 to be stored in any position deemed ideal forparticular expected wind conditions (for example, the parabolic mirrorcould be stored facing the earth as in FIG. 32 assuming clearance forall members (including the absorber tube)). The wind loads would act onthe mirrors 12, and through the mirror supports onto the solar frame 14;as discussed previously re: the “Rolling Rib” design, the forces whichon other solar frames are transmitted only through the pivot points 34at each end of the solar frame 14 can now also be transmitted from the“rib” 16 to the roller assemblies 18, which are mounted on frameworkswith foundations.

As an example, if during a hurricane, the solar frame 14 is storedpointed downward (avoiding wind, rain and hail on the reflective surfaceof the parabolic mirrors 12), the solar frame 14 system could still besubject to wind gusts treating the parabolic mirror as a “wing” andcreating lift, or from gusts pushing upwards on the system. Without the“360 degree rib”, the resistance to this upwards force occurs purelyfrom the solar frame 14 “truss” structure into the two (2) end pivotpoints 34, themselves attached through uprights into a foundation. Withthe “360 degree rib”, installed in one or more locations, the upwards(or other) forces are distributed among the two (2) endpivots/foundation and the rib/roller assembly/frame/foundationlocation(s). Besides spreading the load among three (3), four (4) ormore (vs. only two (2)) locations, the “360 degree rib” dramaticallyreduces the loading, stress and deflections inherent in utilizing thesolar frame 14 truss structure alone with the two (2) pivot points 34currently used on these solar frame 14 designs; this in turn leads toless damage, including mirror breakage, due to excessive windconditions.

The “360 degree rib” system also lends additional support to the solarframe 14 no matter the orientation, as the “rib” engages with all (four(4) as shown in these sketches) roller 18 assemblies. Looking back atFIGS. 18 a-20, depending on the orientation of the solar frame 14, the“Rolling Rib” design engages three (3), two (2), one (1), or in non-usepositions (pointing toward the ground for example), even zero (0) rollerassemblies.

FIG. 31 shows a “360 degree rib” design showing the solar frame 14 in asideways position. FIG. 32 shows a “360 degree rib” shown with parabolicmirror pointing straight down, with “rib” continuing to provide supportthrough all four (4) roller 18 assemblies.

The Mirror Washing/Water reclamation/“gutter” design (may be additive orinstead of the above advantages):

The solar mirrors 12 must be washed periodically to retain their opticalperformance (dust and dirt degrades the performance); filtered“distilled” water (condensate from the steam turbines) is/should be usedfor this. Current designs use a truck which runs between the rows ofsolar mirrors 12, spraying a cleaning solution (from here on, just“water” will be used in the explanatory text) onto the mirrors 12; thewater drips onto the ground and is absorbed or evaporates. This waterbecomes a “consumable”, and in many areas, such as the desertinstallations, this “consumable” is in short supply and thus expensive.

A gutter 28 on the frame 14 can be used to collect the water for reuse.The gutter 28 can be incorporated into the framework of the “RollingRib” design (although the same could be developed without the gutter28); by using the framework, permanent nozzles and a gutter 28 systemcan be attached so that water can be automatically sprayed on themirrors 12 (due to the width of the mirrors 12, it is likely that 2, 3or more nozzle rows will be required; the top line might be deployedfirst, followed sequentially by those immediately below it.) See FIG. 23for a high level overview of the design. FIG. 23 shows a mirror cleaningand solution reclamation system. The gutter 28 “cap” 58 can be fixed orhave the ability to rotate by water pressure actuators or by leveraction to keep sand, dirt or debris from accumulating. FIG. 24 shows a“gutter” 28 with “cap” 58 closed. FIG. 25 shows a “gutter” 28 with “cap”58 open.

The water will be collected in the gutter 28, transferred to a centralarea, filtered and reclaimed for reuse. The gutter 28 would be designedsuch that when not in use collecting water, it is covered to keep itclean of dust, sand and other debris; see FIG. 24. The particular designshown uses a 12 meter gutter 28 (the length of the particular solarframe 14 it is designed for) with end caps attached to each end (the“gutter 28” extrusion has screw boss's 65 incorporated to facilitate theattachment of end plates; the end plates are sized to seal the “gutter”end and cover the space left open by the end view of the “cap” 58).

The “gutter” is mounted on the framework supporting the roller 18assemblies as shown in FIG. 24; note that it is mounted with a slope sothat the water runs to one end of the capped “gutter”. Each 12 meter“gutter” is capped at each end and the collection of the water occurs atthe lowest part of the slope of the unit, with a simple drain pipe 64connecting the water flow from the “gutter”, through a hole in thebottom of the “gutter” to a central water collection pipe 64 for eachline of mirrors 12. These pipes 64 are then connected and drained (orsuctioned, depending on the physical location of all components) into acentral area where the water is separated (there is likely sand andother debris which will sink out or float up) and filtered for reuse.Water pressure pipe 36 capped at one end, pressurized/filled when waterspray is actuated; this pressure tube fits into the “Cap” 58 and has avery small drain (dotted line) to allow it to drain into the “gutter”thus allowing the “Cap” 58 to swing closed once the water is no longercounterweighting it open. “Cap” 58 of the Gutter 28 (slanted to avoidsand/debris buildup). This slanted line 59 represents the bottom edge ofthe mirror 12 from which the water drips. The arrows show where thewater will drip. When the “cap” 58 is closed, it sits on a positive stopof the “gutter” and resists any windblown dust/sand or other debrisentering the “gutter”. Snapfit Counterweight 60 (cut to length to adjustweight and joining “cap” 58 sections. Drain 64 from “gutter” intocollection pipe 36 for solar field. “Gutter” base 63 (capped at eitherend with plates which seal it and cover the “Cap” 58 to avoiddust/sand/debris blowing in). The “gutter” 28 is mounted on a slope witha drain at the low end. There is an extruded hinge 61.

The “gutter” assembly includes an extruded “cap” 58 which is in placeprotecting the “gutter” from collecting dust, sand or other debrisexcept when the water is being sprayed onto the mirrors 12. The “cap” 58and “gutter” are designed with an extruded hinge. The “cap” 58 may bemade up of cut sections placed end to end for the 12 meter length(trying to align a 12 meter length of “cap” 58 and “gutter” might bedifficult, but the “cap” 58 can be slid on in shorter sections (forexample, 1, 2 or 3 meters sections). See FIGS. 24 and 25. When the waterpressure to the mirror spray nozzles turns off, the water in thepressurized/filled tube will slowly drain off through the dotted drainline into the gutter, allowing the cap to close. The extruded hinge 61provides a hard “stop” to the rotation of the “cap” 58. Counterweight 60“snapped”/secured to “Cap” 58. Screw bosses 65 for attaching “gutter”end plates.

This “cap” 58 is designed to be weighted at both ends. The end nearestthe pivot point 34 includes a semicircular arc; once the “cap segments”are slid onto the “gutter” extrusion, a 12 meter water tube 36, cappedat one end and threaded at the other for pressurized water is slid intothese successive semicircular arcs, in effect making the individual “capsegments” into one “cap” 58. See FIGS. 24 and 25.

As the fluid pressure is introduced into the system 10 to supply thespray nozzles, there is a supply of water (via a simple “Y” in thesupply line) to this 12 meter tube 36 so that it fills with water andbecomes heavier than when it is empty. The “gutter cap” 58extrusions/system is designed with this tube over center on the side ofthe pivot point 34 so that this extra weight from the filled tube causesthe “cap” 58 to rotate, lifting the “cap” 58 off of the gutter to allowdrainage water from the minor washing to run into the “gutter”. Notethat there is a small drain hole and pipe 36 between the lowest end ofthe pressure pipe 36 (which is sloped with the “gutter”), through the“gutter cap” 58 into the “gutter” area. While under pressure water willflow in small amounts through this into the “gutter”; the main purposeof this is so that when the pressure is released to stop the spray ofwater onto the minors 12, the pressure pipe 36 can slowly drain itswater back into the “gutter” and become lighter as the pipe 36 empties,eventually allowing the “gutter cap” 58 to swing close, protecting the“gutter” from dust, sand and other debris. See FIGS. 24 and 25.

The end of the “cap” 58 opposite from the pivot point 34 is weighted tohelp it to swing closed when there is no water in the tube. The end hastwo “fingers” on it that go on either side of the “gutter” lip; thepurpose of these is to help reduce the incidence of the wind blowingsand, dust or other debris under the “cap” 58 and into the “gutter”.This end of the “cap” 58 is also designed so that an extruded aluminumweight can be cut to length, slid onto a single “gutter cap” 58 lengthor between two, joining the two, and “squeezed” (or alternatively, “snapfit” onto the “cap(s)” to provide the counterweight 60 to the pressuretube end. This is similar to how lead weights are squeezed onto afishing line. The “snap fit” design is common to aluminum extrusions,and is what is shown in FIG. 24. The aluminum extrusion is pushed ontothe mating piece and the interlocking “wedges” “snap” close (this is asimple, secure, attachment means for a design element like an extruded“gutter cap” 58 counterweight 60). Note that a similar design element isincluded on the water tube side to enable counterweight 60 adjustmentsif required (similar to balancing automotive wheels with lead weights).See FIGS. 24 and 25.

The above design describes using counterweights 60 and the weight of thewater to accomplish the rotation of the hinged “cap” 58 off of the“gutter” to allow water from the mirror 12 to run into the gutter 28.This rotation could also be accomplished mechanically by linkages, leveraction or other means; actuation could be accomplished via waterpressure (perhaps filling bladders which create the force to rotate thegutters 28, but when the water pressure (spraying) stops for a line ofmirrors 12, the bladder drains slowly through a fine orifice so that thegutter 28 stays engaged for a sufficient period of time for it to emptybefore it is rotated again) or through other control means. The intentof all of these types of designs is to minimize the manual opening andclosing of the “gutter” “cap” and to avoid having to equip the solarfield with additional actuation devices.

FIG. 26 is an end view of solar frame 14, “Rolling Rib” including rollerassemblies 18 and water spray/reclamation “gutter”. This overview showsthe Main Water supply 67 for cleaning, the piping of this water to thenozzles/sprayers and to the “gutter” “cap” 58 where the water fills thetube to tilt the “cap” 58 open. Also note the main drain 64. FIG. 27 isa side view of solar frame 14, “Rolling Rib” and water supply 67, gutter28 (shown slanted slightly downward) and drain lines. FIG. 28 is anoverview of water supply 67, “Y” splitting the water between the spraynozzles and the gutter 28 and other features. FIG. 29 is a close-up ofroller assemblies 18 guiding curved “rib” 16 and “gutter” systemincluding water supply 67 to pressure tube which fills to rotate thedevice, thin drain line into gutter 28, main drain and simple snap fitgutter 28 mounting upright. FIG. 30 is a close-up of “gutter” showinghow it snapfits into the mounting bracket 71.

Although the invention has been described in detail in the foregoingembodiments for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention except as it may be described by thefollowing claims.

The invention claimed is:
 1. A support system for holding solar mirrorsof a solar trough system, each of the mirrors having an axis, the systemcomprising: a parabolic trough frame for supporting the mirrors whichrotates about an axis substantially parallel to the ground; a curved ribattached to the frame, curving around the axis substantially parallel tothe ground, the curved rib having an axis, with the axis of the curvedrib parallel to the axis of the parabolic trough frame and parallel withthe axis of each of the mirrors; and at least a first roller having acurvature engaged with the rib along which the rib moves as the framemoves, the rib comprises a profile having a top portion that attaches tothe frame, a central portion extending from the top portion and a bottomportion that engages with the first roller, the rib moving along thefirst roller as the frame rotates about the axis, the first rollercomprises a housing which receives the rib, the first roller comprises aroller disposed in the housing on which the rib moves when the framemoves, and the housing is an aluminum extrusion, the rib has a crosssection that is I shaped and is an I beam with flanges, the rib iscurved about the axis parallel to the I Beam flanges, substantiallyparallel to the ground, the frame has a plurality of interconnectednodes, struts and chords supporting the mirrors from below the mirrors,the rib is an aluminum extrusion, the roller is a bottom roller andincluding at least a first top roller disposed above the bottom portionof the rib, and the bottom roller disposed below the bottom portion ofthe rib.
 2. The system of claim 1 wherein the housing has a firstsegment in which the bottom roller having a curvature is disposed, asecond segment in which the first top roller is disposed, the secondsegment having walls to which the first top roller is attached, and athird segment in which a second top roller is disposed, the thirdsegment having a wall to which the second top roller is attached, thesecond top roller disposed over the rib.
 3. The system of claim 2wherein the surface of the rib approaching the bottom roller is guidedinto position by the curvature of the bottom roller and the beveled endof the rib.
 4. The system of claim 3 wherein the rib includes a rack toengage a pinion.
 5. A roller assembly engaging with a curved ribattached to a frame that holds mirrors of a solar parabolic troughsystem, the rib curving around an axis substantially parallel to theground and comprises a profile with an I shaped cross section and is anI beam with flanges having a top portion that attaches to the frame, acentral portion extending from the top portion and a bottom portion thatengages with the roller assembly, the rib moving along the rollerassembly as the frame moves, the roller assembly comprising: a housingwhich receives the bottom portion of the rib; a first roller disposed inthe housing on which the rib moves when the frame moves; and a secondroller disposed in the housing, the first roller disposed below thebottom portion of the rib and the second roller disposed above thebottom portion of the rib to constrain the rib from lifting out of thehousing due to wind forces on the mirrors.
 6. The roller assembly asdescribed in claim 5 including at least a third roller disposed in thehousing, the first roller disposed below the bottom portion of the riband the second roller and the third roller disposed above the bottomportion of the rib to constrain the rib from lifting out of the housingdue to wind forces or any lateral loads on the mirrors.
 7. A supportsystem for holding solar mirrors of a solar trough system comprising: aparabolic trough frame for supporting the mirrors which rotates about anaxis substantially parallel to ground, the frame has a plurality ofinterconnected nodes, struts and chords supporting the mirrors frombelow the mirrors; a curved rib attached to the frame, curving aroundthe axis substantially parallel to the ground, the curved rib having anaxis, with the axis of the curved rib parallel to the axis of theparabolic trough frame, the rib is an aluminum extrusion; and at least afirst roller having a curvature engaged with the rib along which the ribmoves as the frame moves, the rib comprises a profile having a topportion that attaches to the frame, a central portion extending from thetop portion and a bottom portion that engages with the first roller, therib moving along the first roller as the frame rotates about the axis,the first roller comprises a housing which receives the rib, a rollerdisposed in the housing on which the rib moves when the frame moves, andthe housing is an aluminum extrusion, the rib has a cross section thatis I shaped and is an I beam with flanges, the rib is curved about theaxis parallel to the I Beam flanges, substantially parallel to theground, the roller is a bottom roller and including at least a first toproller disposed above the bottom portion of the rib, and the bottomroller disposed below the bottom portion of the rib.